[vox-tech] HIGHMEM enabled kernel

[Jonathan Stickel]

Karalius, Joseph wrote:
> Output from dmesg:
> ...
> Warning only 896MB will be used.
> Use a HIGHMEM enabled kernel.
> 896MB LOWMEM available.
> ...
> 
> Is HIGHMEM a module that can be loaded at boot time or do I need to
> recompile a new kernel?
> What do I need to do to utilize all 2GB of RAM and why doesn't the Debian
> installer automatically configure the new kernel to use more than 896MB of
> RAM?  It's kind of a bummer to have to do that kind of reconfiguration on a
> fresh install.
> 
> I used a Debian installer from 20040719.  The kernel version is
> 2.4.25-1-386.
> 

Yep, you need a different kernel to use 2GB ram.  I don't know if Debian 
provides a HIGHMEM pre-built kernel or not.  Otherwise, you will need to 
compile a kernel yourself.  The option to look for is:

Processor type and features  --->
  High Memory Support (off)  --->  (choose: off, 4gb, 64gb)

Without high memory support, the max memory used is 896MB, as your dmesg 
confirms.  I read somewhere that using high memory is slower, so the 
rule of thumb is to turn it off up to 1GB of ram.  But for your 2gb, you 
should definitely choose the 4gb option.

Jonathan